Rosen found that teens who have a strong Facebook presence are more likely to suffer from narcissism and mania, and display aggressive behavior. Teens who “overdose” on Facebook report higher instances of depression, anxiety, sleeping problems and stomach aches. They’re also more likely to miss school.

According to the research, students who checked their Facebook page during their observed 15-minute study session get lower grades in school, and have lower rates of reading retention.

On the bright side, Rosen found that Facebook use tends to make teens more empathetic of others.